ProtologueGrandid., Hist. phys. Madagascar pl. 79Bbis 2, 79E 1 (1893).FamilyBombacaceae (APG: Malvaceae)
Chromosome number2n = 60–64, 88Vernacular namesGrandidier’s baobab, giant baobab (En). Baobab malgache (Fr).Origin and geographic distributionAdansonia grandidieri is endemic to south-western Madagascar, from just north of Morondava to just north of Morombe.UsesAdansonia grandidieri is locally called ‘renala’ or ‘reniala’, meaning ‘mother of the forest’ and is the most valuable and most widely exploited of all Malagasy baobabs. The fruit pulp and seeds are eaten fresh. Cooking oil is extracted from the seeds, and in some villages near Morondava the fruits are fed to goats, which digest the pulp but pass the seeds intact. The seeds are then used for oil extraction. Rope is made out of the thick (up to 15 cm) and fibrous bark, particularly for use in canoes. The undried spongy and fibrous wood is sometimes fed to cattle in times of drought; dried sheets of wood have been used as thatch. Wood of dead trees is a substrate for an edible fungus. The spectacular trees play a role in local folklore and religion.Production and international tradeThere is no international trade in the oil extracted from Adansonia grandidieri, but the oil is of good quality and export has been considered. During the late 19th century and early 20th century, seeds were exported to Marseille (France) for the extraction of cooking oil, but low and erratic supply prevented further commercialization. At that time the fruit was exported to England to make small dry tea cakes.PropertiesSeed oil content is 36–39%. The fatty acid composition of the oil is: palmitic acid 38%, stearic acid 4%, oleic acid 23% and linoleic acid 16%. The oil also contains the rare fatty acids: malvalic acid 7%, sterculic acid 8%, and dihydrosterculic acid 2%.DescriptionDeciduous, medium-sized, unarmed tree up to 25 m tall; bole massive, cylindrical, up to 3 m in diameter; outer bark smooth, reddish grey, inner bark thick, with tough fibres; crown flat-topped; branches regularly distributed, mainly horizontal. Leaves arranged spirally, palmately compound, with (6–)9–11 leaflets; stipules up to 2 mm long, caducous; petiole 5–13 cm long, pubescent; petiolules 1–5 mm long; leaflets narrowly elliptical to lanceolate, medial ones 6–12 cm × 1.5–3 cm, margin entire, bluish green, densely hairy with short, clumped, yellowish hairs. Flowers solitary in leaf axils at end of branches, bisexual, regular, 5-merous, large, showy and fragrant; flower bud erect, ovoid, dark brown; pedicel up to 1.5 cm long and 1 cm in diameter, dark brown hairy, jointed; calyx with tube c. 1 cm long, lobes 7.5–8.5 cm × 1.5–2 cm, reflexed, and twisted, reddish brown hairy outside, creamy hairy inside; petals free, narrowly lanceolate to oblanceolate, 9–10 cm × 1.7–2 cm, twisted, white, yellowing with age; stamens numerous, shortly fused at the base, up to 7.5 cm long, white; ovary superior, broadly rounded-conical, c. 1 cm long, lemon-yellow hairy, style longer than central stamens, white, persistent, stigma shortly lobed, white to pinkish. Fruit a large, oblong-ovoid to almost globose berry, with fragile, 2.5–4 mm thick wall, reddish brown hairy, many-seeded. Seeds kidney-shaped, 12–14 mm × 10–12 mm × 9–10 mm. Seedling with hypogeal germination; first 4–5 leaves simple, later ones lobed and finally compound.Other botanical informationAdansonia comprises 8 species, of which 6 are endemic to Madagascar, 1 occurs in continental Africa and is introduced in Madagascar, and 1 is endemic to Australia. Adansonia grandidieri is classified in section Brevitubae together with its nearest relative Adansonia suarezensis H.Perrier, an endangered species from the extreme north of Madagascar. The seeds of the latter species are equally rich in oil and fruit and seeds are eaten, while a bark infusion is taken to treat diabetes. Unique characteristics of Adansonia grandidieri are bluish green and densely stellate-pubescent leaves and a dark brown floral bud.Growth and developmentTaking into account its dry habitat, early growth of Adansonia grandidieri is fast; it can reach 2 m in height in 2 years and 12–15 m, with a bole diameter of 60 cm in 12 years. It produces new leaves at the very beginning of the rainy season and uses water stored in the trunk to support new leaf growth and cuticular transpiration, but stomata remain closed until the roots can supply sufficient water. It is in leaf throughout the wet season from October to May. It flowers in May–August and fruit ripens at the end of the dry season in November–December. Flowers are produced at the tips of leafless branches. They open around dusk and anthesis takes 15 minutes. The open tube of the cuplike calyx can accumulate about 2 ml of nectar, and flowers are frequently visited by fruit bats and fork-marked lemurs, which are probably responsible for pollination.EcologyAdansonia grandidieri is found largely in dry deciduous forest at low altitudes, where it commonly occurs close to waterholes and rivers. Most mature trees are now found in degraded agricultural land.Propagation and plantingPropagation by seed is straightforward. Seeds weigh approximately 1.4 g.HarvestingFruits are collected from the ground or picked from the tree using steps made from wooden pegs hammered into the trunk. To get bark for rope-making, the bark is cut from ground level up to about 2 m high. The scar persists but new bark regenerates over the damaged parts. In some areas, most trees show such scars.To obtain wood for use in thatching, trees are felled and sheets of fibrous wood are peeled from the bole. After drying them in the sun, the sheets are sold in local markets.Genetic resourcesAdansonia grandidieri occurs in reduced and scattered populations. It is threatened by the loss of a significant proportion of mature trees (20% or more), poor regeneration and continuing pressure from man. The trees are now found mainly in degraded forests and agricultural lands. In certain locations, where the larger and fitter individuals have been harvested, genetic decline or loss of fitness of the population is present. Fire, seed predation, cultivation of crops and competition from weeds all contribute to poor regeneration. Incursions of invasive species and changes in native species dynamics are further altering the population ecology. The IUCN carried out an assessment of Adansonia grandidieri in 1998 and classified it as Endangered in the Red List of Threatened Species, indicating that it faces a high risk of extinction in the wild in the near future. Rates of decline in distribution and occupancy over the last 10 years have been in the order of 50%.ProspectsBecause of the endangered status of Adansonia grandidieri, possibilities of planting trees in plantations or as landmarks, as e.g. the kapok tree (Ceiba pentandra (L.) Gaertn.) in East Africa, should be investigated.Major references• Baum, D.A., 1995. A systematic revision of Adansonia (Bombacaceae). Annals of the Missouri Botanical Garden 82(3): 440–471. • Baum, D.A., 1995. The comparative pollination and floral biology of baobabs (Adansonia - Bombacaceae). Annals of the Missouri Botanical Garden 82(2): 322–348. • Baum, D.A., 1996. The ecology and conservation of the baobabs of Madagascar. In: Ganzhorn, J.U. & Sorg, J.-P. (Editors). Ecology and economy of a tropical dry forest in Madagascar. Primate Report. Special Issue 46: 311–328. • Baum, D.A. & Oginuma, K., 1994. A review of chromosome numbers in Bombacaceae with new counts for Adansonia. Taxon 43(1): 11–20. • Bianchini, J.-P., Ralaimanarivo, A., Gaydou, E.M. & Waegell, B., 1982. Hydrocarbons, sterols and tocopherols in the seeds of six Adansonia species. Phytochemistry 21(8): 1981–1987. • Perrier de la Bâthie, H., 1952. Sur les utilités de l’Adansonia grandidieri et les possibilitées de culture. Revue Internationale de Botanique Appliquée et d’Agriculture Tropicale 32: 286–288. • Perrier de la Bâthie, H., 1953. Les Adansonia de Madagascar et leur utilisation. 2ième note. Revue Internationale de Botanique Appliquée et d’Agriculture Tropicale 33: 241–244. • Ralaimanarivo, A., Gaydou, E.M. & Bianchini, J.-P., 1982. Fatty acid composition of seed oils from six Adansonia species with particular reference to cyclopropane and cyclopropene acids. Lipids 17: 1–10.Other references• Baker, H.G. & Baker, I., 1968. Chromosome numbers in the Bombacaceae. Botanical Gazette 129: 294–296. • Keraudren, M., 1963. Pachypodes et baobabs à Madagascar. Science & Nature 55: 2–11. • Mangenot, S. & Mangenot, G., 1962. Enquête sur les nombres chromosomiques dans une collection d’espèces tropicales. Revue de Cytologie et Biologie Végétale 25: 411–447. • Miège, J., 1974. Etude du genre Adansonia 2: Caryologie et blastogenèse. Candollea 29: 457–475. • Rey, H., 1912. Notice sur l’huile de baobab. Bulletin Economique Madagascar 12: 135–140. • M.M.P.N.D., undated. Multilingual Multiscript Plant Name Database [Internet] http://www.plantnames.unimelb.edu.au/ Sorting/ Adansonia.html. Accessed October 2006. • World Conservation Monitoring Centre, 1998. Adansonia grandidieri. [Internet] In: IUCN. 2006 Red list of threatened species. http://www.iucnredlist.org. Accessed August 2006.Sources of illustration• Baillon, M.H., 1889. Histoire naturelle des plantes. In: Grandidier, A. (Editor). Histoire Physique, Naturelle et Politique de Madagascar. Imprimerie Nationale, Paris, France. Pl. 79A–I. • Hochreutiner, B.P.G. & Perrier de la Bâthie, H., 1955. Bombacacées (Bombacaceae). Flore de Madagascar et des Comores (plantes vasculaires), familles 129–130. Firmin-Didot et cie., Paris, France. 21 pp.Author(s)